5.2 Limits to Growth

VOCAB

limiting factors-a factor that controls the growth of a population.

density-dependent limiting factor-limiting factors that depends on population density.

density-independent limiting factor-limiting factor that affects all population in similar ways, regardless of the population density.

Limiting Factors

-acting separately or together, limiting factors determine the carrying capacity of an environment for a species.

Population Size

can be limited by:

1.Competition

2.Predation

3.Parasitism and Disease

4.Unusual Weather

5.Natural Disasters

Density-dependent Limiting

Factors

-includes competition, predation, herbivory, parasitism, disease, and stress from overcrowding.

COMPETITION

-compete for food, water, space, sunlight, and other essentials

-the more individuals living in an area, the sooner they use up the available resources.

PREDATION AND HERBIVORY

-fluctuate-rise and fall as if in waves.

*Predator-Prey Relationships-prey population grows, predator population grows. Prey population falls so does predator.

*Herbivore Effects-same as predator-prey relationship. Leaves grow rapidly so does the herbivore.

*Humans as Predators-humans activity limits populations.

PARASITISM AND DISEASE

-weakening host and eventually causing disease and/or death.

STRESS FROM OVERCROWDING

-fight when over crowed, causing stress

-can lower birthrates, raise death rates, or both.

Density-independent Limiting

Factors

-unusual weather such as hurricans, droughts or floods, and natural disasters such as wildfires, can acts as density-independent limiting factors.

TRUE DENSITY INDEPENDENCE?

-in a smaller population, the moose would have had more food available because there would have been less comeptition.

CONTROLLING INTRODUCTION SPECIES

-reseachers have spent decades looking for natural preadators and pests of hydrilla.